Question

Many interventions studies have shown that mosquito nets treated with insecticide can reduce the morbidity and mortality from malaria in young children in Africa. However, Abdulla et al. (2001) were interested in whether countries that have implemented programs to supply these treated nets to communities with a high prevalence of malaria have seen the benefits highlighted by the intervention studies. In 1977 investigators carried out a cross-sectional study of children less than 2 years of age in 18 villages in Tanzania at the beginning of a marketing campaign to promote the use of treated nets. They collected data on net ownership and other factors by questionnaire (the mothers of the children were interviewed), and took blood samples from the children in the study to assess whether they were infected with malaria parasites (parasitaemia), and also to see whether they were anemic (as a consequence) . The children were also assessed for clinical signs of malaria. Two further surveys were done over the next 2years. A different random sample of children was selected on each occasion.

The investigators identified 985 eligible children, and interviewed the mothers of 827 of these children over the course of the three cross-sectional surveys (16 mothers refused consent, and 142 could not be contacted). Of the 827 interviewees, data from 748 were included in the analysis because 68 children were aged over 2 years at the time of sampling and net status was not known for 11 children.

The following table shows some of the results from the study.

Table1:

	Year of Survey
	1977	1998	1999
Number of eligible children	325	330	330
Number of children analyzed	240	269	239
Number (%) with no net	100 (42%)	49 (18%)	40 (17%)
Number with untreated net	116 (48%)	64 (24%)	53 (22%)
Number with treated net	24 (10%)	156 (58%)	146 (61%)
Number (%) of children with anemia	118 (49%)	83 (31%)	62 (26%)
Number (%) with parasitaemia	151 (63%)	126 (47%)	90 (38%)
Number with splenomegaly	207 (86%)	144 (54%)	117 (49%)

Source: data from Abdulla et, al. (2001)

Answer the following questions about this study

Q1: Is this a descriptive or analytical cross sectional study? Give a reason for your answer (2pt)

Q2: Does it matter that data from some of the eligible children were not included in the analysis? (2pts)

Q3: Describe the results of the study shown in the above table. (2pts)

Q4: Can you calculate the effect of net ownership on the proportion of children with malaria parasitaemia from the table? Why? (2pts)

Answer 1

QUESTION 1: A decriptive case study is a study designed to focus in detail about the participants in an accurate way. The main aim of descriptive case study is to assess a sample or group of population in detail and in depth to collect descriptive data. In this question, I believed it to be a descriptive case study because, in most of the descriptive or detailed study, survey methods are commonly used to collect detailed information. Moreover, the interventions were clearly implemented in 1997 and Abdulla et al ( 2001) were only intrested in how they implemented the programs to eradicate the effect of malaria through treated mosquito nets.

QUESTION 2: Ofcourse yes to me, because an analysis done on the basis of survey on a particular population should be analysized deeply and clearly by collecting extra informations from the eligible participants. Moreover, a huge amount of ideas can be made easily to reduce the disease among the population and give a better results. Further these results can be made accurate and effective interventions can be taken according to the program.

QUESTION 3: Annual cross sectional data were collected at the beginning of the campaign in 1977 and the consecutive 2 years ( 1998 to 1999). Insecticide treated net coverage of children below 2 years rose from less than 10% at baseline to more than half a percentage in 1999. Treated net had a potential effect of 62% on the prevalence of malarial parasitaemia and of 63 %( 27% to 82%) on anaemia.

QUESTION 4: Ownership of nets increased rapidly, non-treated nets - 58% to 83% ; treated nets from 10% to 61%. The after effect of spleenomegaly due to malaria has reduced to 49% . Moreover, the prevalence of anaemia in the study population has decreased from 49% to 26% in the consecutive two years of time. Overall, these results shows a positive impact on the people around Tanzania and from the survey, it is concluded that nets treated with insecticide have a substantial improvement on mortality and morbidity rate when it is distributed to the crowd of Tanzania.